I saw a film or an episode of some sci-fi tv series on Finnish tv around 1981-1988. However the film may be much older (color film though).

I don't remember much of it, because I was quite young then, but this has been bothering me for years. I guess the film affected me a lot, I remember I was a bit scared of it.

There was a plane crash and there were only a few survivors. One of them was pregnant woman who delivered the baby in the plane. The plane landed maybe on a tree or something in a very strange place or different time. There were inhabitants, humans, but almost all the people were women who didn't get children anymore. It appeared that for some reason there hadn't been baby boys for a long time. The people on that place/planet/island(?) were dressed in futuristic simple clothes.

The baby which was born in the plane was, of course, a boy. The women were very curious and wanted to do some research on the baby's physiology etc. At some point it turned out that the few young men living there weren't actually young at all. They were old but wearing masks of young men.

This is all I remember, but I would very much like to see the film again. Does anyone figure out what might be the name of the film (or tv series)?